Currently, mobile communications technologies used in a cellular communications system include frequency division duplex (FDD) and time division duplex (TDD). For the FDD, signals are received and sent on two independent and paired channels, and one guard frequency band that is used to separate an uplink channel from a downlink channel exists between the two channels. For the TDD, although an uplink channel and a downlink channel use a same frequency, the uplink channel and the downlink channel serve as transmission channels in different timeslots. No matter whether the cellular communications system uses the FDD or the TDD, a terminal or a base station is only in either a receiving or sending state at a same frequency or in a same time period. Full-duplex means that a receive end and a transmit end of communication can concurrently perform receiving and sending at a same frequency and in a same time period, which may double a channel capacity in theory. Although a full-duplex technology can increase a channel capacity, a transmitted radio frequency signal is many times stronger than a received radio frequency signal, and as a result, the transmitted radio frequency signal causes interference to the received radio frequency signal.
Currently, a full-duplex wireless transceiver may generally perform self-interference cancellation on an interfering signal in an analog domain or a digital domain by using an antenna, where the performing self-interference cancellation on the interfering signal in the analog domain is particularly important. In the prior art, the full-duplex wireless transceiver performs self-interference cancellation on a radio frequency signal by using an analog device (such as a delayer, an attenuator, and a phase shifter), but adjustable digits of the analog device are limited, which causes a problem that an effect of self-interference cancellation performed by the full-duplex wireless transceiver on the radio frequency signal is not ideal.